Supplementary Material for: Association between Chronic Kidney Disease and Risk of Cataract: A Nationwide Retrospective Cohort Study

Background: Previous studies have established a
relationship between chronic kidney disease (CKD) and cataract, but the
relationship between the severity of renal impairment and risk of
cataract is uncertain. This study investigates the relationship between
the severity of renal disease and cataract in a nationwide sample from
Taiwan. Methods: The cohort from 1-million National Health
Insurance beneficiaries from Taiwan was retrospectively analyzed. All
adult beneficiaries were followed from January 1, 2005 until December
31, 2013, to identify patients who underwent cataract surgeries. On the
basis of the ambulatory care records, those diagnosed with CKD (ICD-9-CM
code: 585) during the follow-up period were enrolled as CKD patients
after careful evaluation. Each patient with CKD was age- and
gender-matched with 4 individuals who did not have CKD. Cox regression
models were applied to compare the hazard of cataract surgery in
individuals with and without CKD. Subgroup analysis was used to compare
patients with end-stage renal disease (ESRD) with age- and
gender-matched non-CKD individuals. ESRD was defined by CKD patients who
need regular renal replacement therapy. The same method was applied to
evaluate hazard ratios (HRs). Results: After age and
gender matching, there were 11,881 patients in the CKD group and 47,524
in the non-CKD group. After control for possible confounding, the
adjusted HR (aHR) of cataract was 1.84 (95% CI 1.73-1.95) for the CKD
group. Subgroup analysis of patients with ESRD (n = 3,209) and non-CKD individuals (n
= 12,836), with matching done on the basis of age and gender, indicated
an aHR of cataract was 2.33 (95% CI 2.10-2.59) for the ESRD group. Conclusions:
This study indicates a relationship between CKD and cataract, and
suggests that the risk for cataract increases with the severity of renal
impairment.